Field of the Invention
The invention relates to an apparatus for driving a piezoelectrically controlled fuel injection valve in an internal combustion engine. The invention also relates to a method for operating the apparatus.
In such an apparatus, an incorrect system response due to a fault in the piezoelectric actuator, the control circuit or faulty connections can be detected by monitoring voltage and current waveforms, for example, during the driving operation.
However, if no discharging takes place due to a fault in the control circuit or if a cable breaks in a charged piezoelectric actuator, then although that state can be detected, it cannot be eliminated because the high resistance of a piezoelectric actuator results in the charge that is applied being maintained for a relatively long time. A fuel injection valve actuated by that piezoelectric actuator will remain open for a corresponding length of time and inject too much fuel, which can cause engine damage.